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I find the tone of absolute certainty off-putting. > The asteroid is falling towards Earth on a fixed trajectory, but the Earth itself is spinning beneath it,

by jMyles 9y ago

I find the tone of absolute certainty off-putting. > The asteroid is falling towards Earth on a fixed trajectory, but the Earth itself is spinning beneath it, one revolution every 24 hours. This corresponds to around 1,000 miles an hour in the region of interest. So arriving ten minutes earlier or later would have placed the impact some 150 miles further to the East or West. And if this had happened, the asteroid would have missed the shallow gypsum-rich continental shelf, and encountered only the oceans on either side. No gypsum in the impact zone, no sulphuric acid haze, no long deep winter. While things might have been pretty rough for anything living within a couple of thousand miles or so, the rest of the world would hardly have noticed. > ... > And if the meteorite had arrived ten minutes earlier, or ten minutes later, it would still no doubt have inflicted devastation, but the dinosaurs would still be here and you wouldn't. While the specific hypothesis about the chemistry of the impact zone is very cool - and drilling and analysis a very compelling project - I think that the credibility of the conclusion is clouded a bit by the idea that the reader is supposed to accept with certainty that the events unfolded exactly as the author describes to within a 10-minute window.

DarkTree 9y ago
I agree with your skepticism of the author's conclusion. For example, we only know that the location/timing of the asteroid impact was so devastating because it did in fact hit there and so we were able to study it and find the "smoking gun", in other words, it wasn't obvious. But how can you assume that if it hit somewhere else at some other time that we wouldn't have found some hidden life-ending mechanism in that event as well?
ChuckMcM 9y ago
I would be interested to understand the affront you feel. When I read it I heard the process of elimination that scientists went through ruling out all of the ways it could not have happened, leaving only this explanation which fit the facts. He also explained the 10 minute notion based on earth rotation and some of the other work that had been done which had tried to explain other aspects of the extinction (like why did all the plant life die off?) As a result I felt the author had done an acceptable job of explaining why he was so certain. Clearly that didn't work for you and I would like to understand that.
- neaden 9y ago
  I've heard multiple explanations for what exactly killed the dinosaurs off, and every time the person giving them has been fairly certain and had a good explanation for why. Hearing another explanation is always going to make me skeptical now. Edit: To give some more details this still doesn't explain why dinosaur specie diversity was going down before the impact, or why no small non-avian dinosaur species survived anywhere in the world when so many mammal, reptile, and avian-dinosaur species did.
  - ChuckMcM 9y ago
    Thank you for your response. I am asking because I am interested in the communication and presentation of scientific results to diverse audiences. I have observed that the notion of 'current best explanation for the observed results' can be misinterpreted. All science is the process of people trying to find an alternate explanation, other than the one proposed, that fits the evidence and can make predictions about evidence that has yet to be found. It is the totality of the observed facts that the explanation explains, and the ability to accurately predict other facts that will be found assuming the explanation is the one that really explains things. What I've observed is, as you have described, that during the evolution of the scientific investigation, especially when hypotheses are shown to be incomplete and are updated, that communication is heard as a "different" answer rather than as a more refined answer. As my daughter observed about meteorologists predicting rain, "they don't really know, they are just guessing." And that is true with all science, there is no Arc of Knowledge where we can look up the answers to the questions in the back. The author of the article clearly felt convinced, based on the evidence presented, that this hypothesis about the events that took place is the most accurate idea we have to date. And they showed how other possible explanations had been explored, how predictions (about Iridium) had been made and validated, how estimates of mass and size were made, how the physics of the impact compared to those on other planetary bodies that don't have erosion, Etc. And that confidence they felt came across as 'certainty'. And yet, their own confidence and their sharing of how they came to have that confidence is off putting. Which is, I am fairly certain, exactly the opposite of what the author had hoped for. They had hoped to share their understanding so that the reader could be confident in their own belief that this is, to the best of our knowledge, exactly what happened so long ago.
Reason077 9y ago
"The asteroid is falling towards Earth on a fixed trajectory, but the Earth itself is spinning beneath it, one revolution every 24 hours. This corresponds to around 1,000 miles an hour in the region of interest. So arriving ten minutes earlier or later would have placed the impact some 150 miles further to the East or West." If the asteroid had arrived 10 minutes later on the same trajectory, the Earth would have moved about 18,000 km through space and it would have missed us entirely!
- cossatot 9y ago
  It's unlikely that the asteroid would have come so close (18,000 km is closer than GPS satellites) without being pulled to Earth because of the planet's gravitational field.
  - ChuckMcM 9y ago
    At 40,000 MPH (or about 18 kM/s) at best, the Earth could deflect it somewhat from 18,000 miles out. Remember that escape velocity is only 11 kM/s, so even if the asteroid grazed the atmosphere if it didn't slow by more than 7 km/S it would have just shot back out into space. The GP is correct, if the asteroid is on an orbit that is outside of the ecliptic plane. But to the article author's point, had it landed on nothing but ocean it would have had a different outcome. I believe the +/- 10 minutes conceptually was a way of illustrating some of the things that would have changed the outcome.

by jMyles 9y ago

DarkTree 9y ago

I agree with your skepticism of the author's conclusion. For example, we only know that the location/timing of the asteroid impact was so devastating because it did in fact hit there and so we were able to study it and find the "smoking gun", in other words, it wasn't obvious. But how can you assume that if it hit somewhere else at some other time that we wouldn't have found some hidden life-ending mechanism in that event as well?

ChuckMcM 9y ago

I would be interested to understand the affront you feel. When I read it I heard the process of elimination that scientists went through ruling out all of the ways it could not have happened, leaving only this explanation which fit the facts. He also explained the 10 minute notion based on earth rotation and some of the other work that had been done which had tried to explain other aspects of the extinction (like why did all the plant life die off?) As a result I felt the author had done an acceptable job of explaining why he was so certain. Clearly that didn't work for you and I would like to understand that.

neaden 9y ago
I've heard multiple explanations for what exactly killed the dinosaurs off, and every time the person giving them has been fairly certain and had a good explanation for why. Hearing another explanation is always going to make me skeptical now. Edit: To give some more details this still doesn't explain why dinosaur specie diversity was going down before the impact, or why no small non-avian dinosaur species survived anywhere in the world when so many mammal, reptile, and avian-dinosaur species did.
- ChuckMcM 9y ago
  Thank you for your response. I am asking because I am interested in the communication and presentation of scientific results to diverse audiences. I have observed that the notion of 'current best explanation for the observed results' can be misinterpreted. All science is the process of people trying to find an alternate explanation, other than the one proposed, that fits the evidence and can make predictions about evidence that has yet to be found. It is the totality of the observed facts that the explanation explains, and the ability to accurately predict other facts that will be found assuming the explanation is the one that really explains things. What I've observed is, as you have described, that during the evolution of the scientific investigation, especially when hypotheses are shown to be incomplete and are updated, that communication is heard as a "different" answer rather than as a more refined answer. As my daughter observed about meteorologists predicting rain, "they don't really know, they are just guessing." And that is true with all science, there is no Arc of Knowledge where we can look up the answers to the questions in the back. The author of the article clearly felt convinced, based on the evidence presented, that this hypothesis about the events that took place is the most accurate idea we have to date. And they showed how other possible explanations had been explored, how predictions (about Iridium) had been made and validated, how estimates of mass and size were made, how the physics of the impact compared to those on other planetary bodies that don't have erosion, Etc. And that confidence they felt came across as 'certainty'. And yet, their own confidence and their sharing of how they came to have that confidence is off putting. Which is, I am fairly certain, exactly the opposite of what the author had hoped for. They had hoped to share their understanding so that the reader could be confident in their own belief that this is, to the best of our knowledge, exactly what happened so long ago.

Reason077 9y ago

"The asteroid is falling towards Earth on a fixed trajectory, but the Earth itself is spinning beneath it, one revolution every 24 hours. This corresponds to around 1,000 miles an hour in the region of interest. So arriving ten minutes earlier or later would have placed the impact some 150 miles further to the East or West." If the asteroid had arrived 10 minutes later on the same trajectory, the Earth would have moved about 18,000 km through space and it would have missed us entirely!

cossatot 9y ago
It's unlikely that the asteroid would have come so close (18,000 km is closer than GPS satellites) without being pulled to Earth because of the planet's gravitational field.
- ChuckMcM 9y ago
  At 40,000 MPH (or about 18 kM/s) at best, the Earth could deflect it somewhat from 18,000 miles out. Remember that escape velocity is only 11 kM/s, so even if the asteroid grazed the atmosphere if it didn't slow by more than 7 km/S it would have just shot back out into space. The GP is correct, if the asteroid is on an orbit that is outside of the ecliptic plane. But to the article author's point, had it landed on nothing but ocean it would have had a different outcome. I believe the +/- 10 minutes conceptually was a way of illustrating some of the things that would have changed the outcome.